Antimicrobial Interfaces - Biointerfaces: Where Material Meets Biology - page 415

Protocol to measure cell-cell adhesion within a P.aeruginosa biofilm grown in a CDFF using
Atomic Force Microscopy (AFM)

To measure gallium exposure effect, use the set of
gallium exposed biofilm coated glass substrate and
corresponding silicon (Si) nanoprobe

To measure silver exposure effect, use the set of
silver exposed biofilm coated glass substrate and
corresponding silicon (Si) nanoprobe

To measure control glass exposure effect, use the
set of control glass exposed biofilm coated glass
substrate and corresponding silicon (Si) nanoprobe

Use the AFM in force-distance (F-D) mode, use
an AFM fluid cell with PBS (pH 7.2)

Set max. force at 50nm,
max. displacement at ±1.5μm

Cantilever-substrate combination should not be
changed during the experiment to eliminate the
possibility of altering the AFM cantilever spring
constant

Measure forces for each sample at least 10
different points

Monitor the 'offsets' between the contact and non-contact regions continuously to ensure
that the Si tip approached the sample

Use force-distance curves to calculate interactive forces using F= k sp ∆z
(F= force in 'nN'; ksp=spring constant in 'Nm -1 ' and ∆z is the Z distance from the control point
to the pull-off point in 'nm')

Negative values of F represent attractive forces, and
the positive values represent repulsive forces

Figure 14.3 A protocol to evaluate cell-cell adhesion within P. aeruginosa biofilm exposed to antibacterial metal-doped glasses.